Electrostatic deflector for electron beam exposure apparatus

ABSTRACT

An electron beam radiation apparatus having an electrostatic deflector capable of deflecting the electron beam with high accuracy and with a reduced displacement of the deflection position, is disclosed. The electrostatic deflector comprises a cylindrical holding member made of an insulating material and a plurality of electrodes separately fixed from each other inside of the holding member with at least a part of the surface thereof covered with a metal film. The holding member has a plurality of wedge-shaped fixing holes corresponding to the portions of the electrodes where they are fixed, respectively, the holes having a larger diameter on the outer peripheral surface than on the inner peripheral surface of the holding member. The electrodes are fixed on the holding member in such a manner that a molten joining metal is injected in the fixing holes with the electrodes arranged on the holding member and the joining metal is hardened in close contact with the metal film of the electrodes. The electrodes fixed on the holding member are so shaped that the inner wall of the holding member is invisible from the cylinder axis of the holding member. The electrodes have a metal thin film formed, by vapor deposition, on the inner wall surface of the electrodes after being fixed on the holding member.

BACKGROUND OF THE INVENTION

The present invention relates to an electrostatic deflector used fordeflecting an electron beam in an electron beam radiation apparatus suchas an electron beam exposure apparatus or an electron microscope.

An electron beam can be reduced to several tens of nm in diameter, andapparatuses for radiating an electron beam such as an electronmicroscope or an electron beam exposure apparatus are used. Theseelectron beam radiation apparatuses use a deflector for changing theexposure position of the electron beam converged on a sample. Thedeflector used for this purpose includes an electromagnetic deflectorhaving a large deflection range but a comparatively low response rate oran electrostatic deflector having a narrow deflection range but a highresponse rate or a combination thereof. The present invention relates toan electrostatic deflector. Although the description that follows refersto the electrostatic deflector of the electron beam exposure apparatus,as an example, the present invention is not limited to such an deflectorbut is applicable to any electrostatic deflector used with an electronbeam radiation apparatus.

In recent years, the ever-increasing miniaturization and density ofintegrated circuits has developed to such an extent that a furtherminiaturization is difficult to achieve by the photolithography whichhas long been a main stay of techniques for forming a fine pattern. Inview of this, an exposure method using a charged particle beam such asan electron beam or an ion beam or a new exposure method using X rayshave been studied and realized as a technique replacing thephotolithography. Of all these methods, electron beam exposure, whichcan form a pattern as fine as not more than 0.1 μm using an electronbeam is in the spotlight. At the same time, the electron beam exposureapparatus is required to have an operating stability, a high throughputand a finer micromachinability as a part of a semiconductor massproduction system.

A typical conventional electron beam exposure apparatus employsdeflection means configured with a combination of an electromagneticdeflector and an electrostatic deflector. The electromagnetic deflectoris called a main deflector, and the electrostatic deflector an auxiliarydeflector. Generally, the deflection range (main deflection range) ofthe electromagnetic deflector is divided into several areas(subdeflection range) each smaller than the deflection range of theelectrostatic deflector, the deflection position of the electromagneticdeflector is located at the center of each subdeflection range, and eachsubdeflection range is deflected by the electrostatic deflector. Aprojection lens for radiating an electron beam of an appropriate sectionon a wafer is built into the column of the electron beam exposureapparatus. The electromagnetic deflector and the electrostatic deflectorare arranged substantially integrally with the projection lens, orspecifically, the electrostatic deflector is housed in theelectromagnetic deflector.

The use of a metal of a superior machinability and high precision but ofa high conductivity for the electrostatic deflector (auxiliarydeflector) or the surrounding parts leads to the inconvenience of alower response rate of the electromagnetic deflector (main deflector)due to an eddy current. This poses a serious problem for the electronbeam exposure apparatus requiring a high throughput.

In an attempt to reduce the eddy current, an electrostatic deflector hasbeen formed by plating (for example, with Ni and Au as a base and asurface, respectively) the interior of a cylindrical insulating material(such as alumina). To avoid the problems of the machining precision andthe difficulty of the plating process, however, the current practice isto make an electrostatic deflection electrode by grinding an AlTiC(compound of alumina and titanium carbide) ceramic having an almostideal resistivity and plating it with platinum, which electrode is fixedin a hollow cylinder of an insulative alumina ceramic to make anelectrostatic deflector.

FIGS. 1A to 1C show a conventional electrostatic deflector of anelectron beam exposure apparatus. FIG. 1A shows an outer configurationof the electrostatic deflector, FIG. 1B a top plan view as taken in line1B-1B′ in FIG. 1A, and FIG. 1C a sectional view taken in line 1C-1C′ inFIG. 1B.

The electrostatic deflector 10 shown in the diagrams is arranged in anelectromagnetic deflector constituting a main deflector (not shown) andused as an auxiliary deflector of an electron beam exposure apparatus.As shown, the electrostatic deflector 10 includes a group of electrodes11, and a hollow cylindrical holding member 12 with the electrodes 11fixed therein.

The electrodes 11 are composed of eight AlTiC ceramic electrode membersE₁ to E₈. The electrode members E₁ (i: 1 to 8) are fixedly arrangedsymmetrically about an axis in the holding member 12 (FIG. 1B). Eachelectrode members E₁ is ground into the same shape with the surfaceformed of a metal film. This metal film is made of a metal of platinumgroup such as ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os),iridium (Ir) or platinum (Pt) and formed directly on each surface of theconductive ceramics by electroplating.

The electron beam is a flow of electrons, which when impinged on aninsulating material, accumulates the electric charge on the surface ofthe insulating material. The electric charge thus accumulated has aneffect on the surrounding electric field. The electrostatic deflector isfor generating an electric field in the electrodes 11 by applying avoltage to each electrode member E₁ and deflecting the incident electronbeam with the force of the electric field. The problem is that in thecase where the electric field is disturbed by the charge accumulated onthe surface of the surrounding holding member 12, the desired deflectionamount cannot be obtained. In view of this, the conventionalelectrostatic deflector shown in FIGS. 1A to 1C has a structure in whicheach electrode member Ei has a crank-shaped section so that the innersurface of the holding member 12 is not directly visible from the centeraxis of the cylinder. With this shape, even when the electron beam isdisturbed as it passes through the cylinder, the electrons disturbedimpinge on one of the electrode members Ei and are prevented fromreaching the inner surface of the holding member 12.

On the other hand, the holding member 12 is required to insulate theelectrode members E_(i) from each other and is made of a ceramicinsulating material such as alumina. This holding member 12 is formedwith wedge-shaped fixing holes 31 having a larger diameter on the outerperipheral surface than on the inner peripheral surface of the holdingmember 12. These fixing holes are used for fixing the electrodes 11(eight electrode members E₁ to E₈) inside, and two fixing holes (for atotal of 16) are formed for each electrode member E_(i). The inner wallportion of each fixing hole 31 is formed with joining metal pads 16, 17made of Ti or molybdenum-manganese (Mo—Mn), as a main component, bymetallization.

FIG. 2A shows an electrode member E_(i) making up the electrodes, andFIG. 2B a sectional view of the electrode member E_(i) and the holdingmember on which the electrode member E_(i) is fixed.

Eight electrode members Ei of the same shape are used for constitutingthe electrodes 11 of the electrostatic deflector and are made bygrinding the AlTiC ceramics and plating the surface with platinum. Forfabricating the electrode members E_(i), the first step is to grind theminto the same shape. Each electrode member E_(i), after the surfacethereof is cleaned, is formed with a conductive metal pad 13 bymetallization with titanium (Ti), as a main component, constituting apart impressed with a voltage from the driver. Further, joining metalpads 14, 15 of Ti, as a main component, are formed by metallization attwo arbitrary points for fixing the electrode member E_(i) to theholding member 12. The size of each of the metal pads 13 to 15 is keptto a minimum. Then, platinum (Pt) is directly formed on the surface ofeach electrode member E_(i) by electroplating to the thickness of notmore than 2 μm.

Each electrode member E_(i), to be fixedly arranged in the holdingmember 12, is inserted into the holding member 12 while being fixedlyset in position with high accuracy by an assembly jig, and a smallamount of the molten metal solder material 18 is injected and hardenedin the fixing holes 31 formed in the holding member 12 (FIG. 2B). As aresult, the joining metal pads 14, 15 formed on the electrode memberE_(i) and the joining metal pads 16, 17 formed on the holding member 12are fixed through a joining metal 18. In other words, each electrodemember E_(i) is firmly fixed in a predetermined relative position.Instead of injecting the joining metal 18 in the fixing hole 31, anadhesive may be used.

The electrostatic deflector of the conventional electron beam exposureapparatus has the configuration described above. In actual practice,however, the deflection position is displaced, though to a small degree,by about several tens of nm. Even this slight displacement has appearedas a problem in recent years as a finer and finer resolution has beenrequired of the electron beam exposure apparatus.

SUMMARY OF THE INVENTION

The object of the present invention is to realize an electrostaticdeflector higher in accuracy than the electron beam radiation apparatusdescribed above by reducing the displacement of the deflection positionthereof.

In order to achieve the object described above, according to the firstaspect of the present invention, there is provided an electrostaticdeflector of an electron beam radiation apparatus, wherein a pluralityof electrodes are fixed separately from each other on the inside of acylindrical holding member made of an insulating material, and a metalthin film is deposited by evaporation on the inner wall surface of theelectrodes, as shown in FIGS. 1A to 1C.

Specifically, an electrostatic deflector of an electron beam radiationapparatus according to the first aspect of the invention comprises acylindrical holding member made of an insulating material and aplurality of electrodes fixed in spaced relation with each other on theinside of the holding member and having at least a part of the surfacethereof grown with a metal film, wherein the holding member has aplurality of wedge-shaped fixing holes formed in positions correspondingto the positions where the electrodes are fixed, the fixing holes have alarger diameter on the outer peripheral side than on the innerperipheral side of the holding member, the electrodes are arranged andfixed on the holding member by injecting a molten joining metal into thefixing holes, the joining metal is hardened in close contact with themetal film, the inner wall surface of the holding member is invisiblefrom the cylinder axis of the holding member with the electrodes fixedon the holding member, and the electrodes have a metal thin film formedby evaporation on the inner wall surface of the electrodes after fixingthe electrodes on the holding member.

After the assembly, the metal thin film is formed on the inner wallsurface of the electrodes by vapor deposition in such a manner that theholding member is held in vacuum and while being rotated, the vaporsource constituting the material of the metal thin film is heated whilemoving it in the holding member.

FIGS. 3A to 3C are diagrams showing basic structures of electrostaticdeflectors for an electron beam radiation apparatus according to asecond aspect of the invention, in which FIG. 3A shows a first basicstructure, FIG. 3B a second basic structure and FIG. 3C a third basicstructure.

As shown in FIGS. 3A to 3C, the electrostatic deflectors for an electronbeam radiation apparatus according to the second aspect of the inventioncomprises a cylindrical holding member 52 made of a non-conductivematerial and a plurality of electrodes 11 having at least a partiallyconductive surface and fixedly separate from each other along the innerperipheral direction. In the first basic structure of the electrostaticdeflector according to the invention, as shown in FIG. 3A, the holdingmember 52 has, in the portions thereof facing the space between eachadjacent electrodes, openings 60 in the direction parallel to the axisof the cylinder. In the second basic structure according to theinvention, as shown in FIG. 3B, on the other hand, a plurality of theelectrodes 11 extend in the direction of emission of the electron beamfrom the holding member 52. In the third basic structure according theinvention, as shown in FIG. 3C, the holding member has a plurality ofindependent holding units 52 a, 52 b the total length of which issufficiently smaller than the length of the electrode 11.

Various analyses show that the displacement of the deflection positionis probably caused by the charge-up of the electrostatic deflector.Before assembly of the electrostatic deflection shown in FIGS. 1A to 1C,the electrode members and the holding member are cleaned into a stateapparently completely free of fouling and the assembly work is conductedin the clean environment. In fact, a check of the state of the innerwall surface of the electrode members after assembly has not revealedany fouling according to the state-of-the-art detection method.Nevertheless, the present inventor has estimated that a fouling thatcannot be detected may have caused the charge-up. As described above,the electrostatic deflector shown in FIGS. 1A to 1C is fabricated byforming a metal (platinum) film on the surface of the electrode membersby plating or by vapor deposition, followed by fixing the electrodemembers on the holding member with a joining metal. In the case where ametal solder is used as the joining metal, the flux contained in themetal solder attaches, taking a circuitous route, to the inner wallsurface of the electrode at the time of heating. Also, when an adhesiveis used in place of the joining metal, an organic material may attach orthe adhesive may ooze out on the inner wall surface of the electrodes atthe time of heating. Further, the surface of the metal film formed byplating comes into contact with a liquid with many chemical substancesdissolved therein during the plating process. Even after thepost-plating cleaning, therefore, some residue is expected to remain onthe surface. According to the state of the art, such fouling cannot bedetected but may have caused a small charge-up leading to thedisplacement of the deflection position.

The present inventor thought that this fouling was unavoidably causedduring the assembly process and that the charge-up can be avoided byforming a new metal thin film covering the fouling. The structure of theelectrostatic deflector in which, as shown in FIGS. 1A to 1C, theelectrodes are fixed on the inner wall surface of an elongate cylinder,however, precludes the use of the sputtering for forming a metal thinfilm on the inner wall surface of the electrodes. In view of this, theholding member with the electrodes fixed thereon is held in vacuum, awire member constituting the material of the metal thin film is held onthe cylinder axis of the holding member, and rotating the holdingmember, the wire member is moved while being heated in the holdingmember.

In this way, a metal thin film is formed on the inner wall surface ofthe electrodes by vacuum deposition with the wire member as a vaporsource. In vacuum deposition, the temperature of the holding member withthe electrode members fixed thereon increases, and the electrode membersare required to be fixed with a metal. In this case, therefore, abonding method having a low heat resistance cannot be used. The metalthin film formed on the inner wall surface of the electrodes is notexposed to the mechanical force and therefore is not required to be amechanically strong film. Further, the electrode members are acrank-shaped as shown in FIGS. 1A, 1B. Therefore, the materialevaporated from the wire member arranged on the cylinder axis proceedsstraight ahead and attaches to the inner wall surface of the electrodemembers but not to the inner wall surface of the holding member. As aconsequence, the insulation between the electrodes is not adverselyaffected.

In fact, the displacement of the deflection position can be avoided byforming a metal thin film on the inner wall surface of the electrodeafter assembly.

The present inventors have discovered that another cause of the chargeup is the reflected electrons, the secondary electrons and theevaporated components of the sample attaching to the surface of theholding member. The charge up from this viewpoint will be explained withreference to FIG. 4.

In the electron beam exposure apparatus, the electrostatic deflector 10is arranged at a position nearest to a sample (wafer) 1 in theelectromagnetic deflector 9. The surface of the sample 1 is formed witha resist layer 2 and irradiated with an electron beam 3. The electronbeam radiated on the resist layer 2 is absorbed into the resist layer 2and sensitizes it, although part of the electron beam is reflected bythe surface of the resist layer 2 and returns to the electrostaticdeflector 10. Also, part of the secondary electrons scattered in theresistor layer 2 or absorbed into and released from the resist layer 2also returns to the electrostatic deflector 10. These reflectedelectrons and the secondary electrons are accumulated at a position nearthe end of the holding member 12. Also, the electron beam 3 enters thesample 1 by being deflected while passing through the electrostaticdeflector 10 and the electromagnetic deflector 9. In the case where thedeflection amount is large, the electron beam 3 enters the sample at aposition near to the surface of the extension of the electrode membersE_(i). The reflected electrons or the secondary electrons from thisposition, even though the electrode members E_(i) are in the shape ofcrank as described above, are more liable to arrive at the surface ofthe holding member 12. The problem resulting from the fact mentionedabove is that the charge is liable to be accumulated (charged up)especially at a portion of the holding member 12 nearer to the sample 1,thereby leading to an error of the exposure position of the electronbeam.

The charge-up occurs also due to another cause. In the electron beamexposure apparatus, the interior of the column and the interior of thechamber coupled to the column for the exposure processing are normallykept in high vacuum state. Actually, however, due to the evaporation ofthe resist or the like, a compound (fouling) having burnt carbon as amain component is generated by the radiation of the electron beam. Thisfouling is not a good conductor, and therefore the charge-up occurs onthe electrode surface, disturbs the electric field, and thus poses theproblem of an error occurring at the exposure position of the electronbeam. This problem is especially conspicuous on the electrostaticdeflector (subdeflector) located in the neighborhood of the wafer coatedwith the resist.

In the prior art, the electrostatic deflector itself is replaced with anew one when the charge-up reaches a certain amount. The work ofreplacing the electrostatic deflector, however, requires the temporaryloss of the high vacuum state (i.e. temporary exposure to theatmosphere) in the column and the chamber. During the restart-up of theexposure apparatus after the replacing work (during the initializationof the deflection data applied to each deflector, for example), theapparatus is stationary, thereby leading to a lower throughput. To copewith this problem, a method called the “in-situ” cleaning for removingthe fouling without exposing the interior of the column and the chamberto the atmosphere has been used. In this method, a very small amount ofa gas having oxygen as a main component is introduced into theapparatus, and in this thin gas atmosphere, a high-frequency power isapplied to the electrostatic deflection electrode and thus an oxygenplasma is generated to remove the fouling by ashing. This “in-situ”cleaning, however, sputters the conductive substances forming a metalfilm on the electrode surface or a substance contaminating the electrodesurface. These substances attach to the non-conductive surface of theholding member 12 and reduce the insulation resistance between theelectrodes or otherwise cause the charge-up unexpectedly, resulting in alower positional accuracy of exposure.

As shown in FIGS. 1A to 1C, a plurality of electrodes 11 are fixed onthe interior of the holding member, and the interior of the cylinderdirectly faces the space between each adjoining electrodes. The chargeis accumulated in these space between the electrodes, which affects theinternal electric field of the cylinder. Also, the insulation resistancebetween the electrodes is affected by the surface resistance of theportion of the holding member corresponding to each space between theelectrodes. As shown in FIG. 3A, with the first basic structure of theinvention, a plurality of openings 60 extending in the directionparallel to the axis of the cylinder are formed in the portions of theholding member 52 corresponding to the space between the electrodes, andtherefore the portion of the holding member 52 corresponding to thespace between the electrodes is reduced. Thus, as compared with theprior art, the amount of the charge accumulated is reduced for a reducedeffect on the electric field. Further, the area (width) of the portionsof the holding member 52 corresponding to the space between theelectrodes is reduced for an increased surface resistance. As a result,the insulation resistance between the electrodes increases to such anextent that even when a conductive substance or a contaminated substanceattaches to the particular portion, the effect thereof can be reduced.

As described above, the problem is posed mainly in the case where acharge-up of the holding member occurs or a conductive substance or acontaminated substance attaches to the portion of the holding membernearer to the sample. As shown in FIG. 3B, with the second basicstructure according to the invention, a plurality of the electrodes 11extend in the direction of electron beam emission from the holdingmember 52, which is located at a distance from the sample. Therefore,the charge-up or the attachment of the conductive or contaminatedsubstance is difficult to occur. Incidentally, the holding member isdesirably one third or more of the length of the electrode away from thesample.

As shown in FIG. 3C, the third basic structure according to theinvention, like the first basic structure, is intended to reduce thearea of the holding member 52 corresponding to the space between eachadjoining electrodes. In the first and second basic structures, theholding member 52 has a predetermined shape, and a plurality of theelectrodes 11 are arranged in predetermined relative positions by beingfixed on the holding member 52. With the third basic structure, incontrast, the holding member is divided into a plurality of independentholding units 52 a, 52 b, which initially have no predetermined relativepositions. In view of this, in the third basic structure, a plurality ofthe electrodes and a plurality of the holding units are fixed inposition for determining the relative positions of a plurality of theelectrodes. In other words, a plurality of the electrodes also functionas a structural member to determine relative positions.

It is also possible to employ a combination of the first to third basicstructures described above. Further, the first aspect of the inventioncan be applied to the second aspect, so that after assembling theelectrostatic deflector having the third basic structure from the firststructure, the deposition by evaporation is desirably effected on theelectrode surface as in the first aspect.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and advantages of the electron beam exposure apparatusaccording to the present invention will be more clearly understood fromthe following description taken in conjunction with the accompanyingdrawings, in which:

FIGS. 1A to 1C are model diagrams showing the appearance and an internalconfiguration of the electrostatic deflector of the conventionalelectron beam exposure apparatus;

FIGS. 2A and 2B are diagrams showing the conventional electrode memberand the state in which the electrode member is fixed on the holdingmember; and

FIGS. 3A to 3C are diagrams showing basic structures of an electrostaticdeflector according to this invention.

FIG. 4 is a diagram for explaining the charge-up and the attachment ofcontaminated substances at the portion nearer to the sample.

FIG. 5 is a sectional view of a vacuum vapor deposition apparatus usedfor vacuum vapor deposition of a metal thin film on the inner wallsurface of the electrostatic deflector according to an embodiment.

FIG. 6 is a perspective view showing a configuration of an electrostaticdeflector according to a second embodiment of the invention.

FIG. 7 is a perspective view showing a configuration of an electrostaticdeflector according to a third embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The electrostatic deflector according to this embodiment has thestructure shown in FIGS. 1A to 1C and FIGS. 2A, 2B, and is differentfrom the prior art only in that platinum is deposited by evaporation invacuum on the inner wall surface of the electrode members E_(i) afterassembly. The assembled state of FIGS. 1A to 1C is obtained by the samesteps as in the prior art. The only difference is the step of depositingplatinum by evaporation in vacuum on the inner wall surface of theelectrode members E_(i).

FIG. 5 is a sectional view of a vapor deposition apparatus fordepositing platinum by evaporation in vacuum on the inner wall surfaceof the electrode members E_(i) of an electrostatic deflector accordingto an embodiment.

In FIG. 5, reference numeral 21 designates a base of the vapordeposition apparatus, on which a cylindrical side wall 22 is fixedthrough a packing 25. A path 23 connecting to a vacuum pump (not shown)is formed in the side wall 22. An upper plate 24 is mounted on the sidewall 22 through another packing 25. Once the upper plate 24 is mountedand the vacuum pump is activated, the interior of the chamberpartitioned by the base 21, the side wall 22 and the upper plate 24 isevaculated. The base 21 has a rotary base 26 thereon, on which a rotarytable 27 is arranged through a bearing 28. The rotary table 27 is formedof gear teeth in mesh with a gear 44 rotated by a rotational motor 46.The rotary table 27 is rotated in accordance with the operation of therotational motor. The forward end of the rotary table 27 is adapted tohold the electrostatic deflector 10. A rotation control member 29, whichis mounted above the electrostatic deflector 10 thus held, is fixed onthe side wall 22 through a mounting member 30. A platinum wire member 41constituting a vapor deposition material is passed along the center axisof the electrostatic deflector 10 thus held. The lower portion of thewire member 41 is attached on a Z stage 42 constituting a verticaltravel mechanism on the one hand and the upper portion thereof isattached to a Z stage 43. The Z stages 42, 43 are connected to a powersupply not shown and can heat the wire member 41 by supplying a currentthereto while at the same time moving the wire member 41 vertically.

The electrostatic deflector 10, assembled in the same manner as in theprior art, is held on the rotary table 27 with the upper plate 24 andthe rotation control member 29 removed therefrom. After that, therotation control member 29 is mounted, and the wire member 41 isinserted into the electrostatic deflector 10 and mounted on the Z stages42, 43. Further, the upper plate 24 is fixed and the interior of thechamber is vacuumerized. While rotating the electrostatic deflector 10by rotating the rotary table 27, the wire member 41 is heated bysupplying a current thereto while moving it vertically. The platinumevaporated from the wire member 41 is deposited on the inner wallsurface of the electrode members E_(i) thereby to form a thin film. Inthe process, since the electrode members E_(i) are crank-shaped, theplatinum is not deposited on the inner wall surface of the holdingmember 12. Thus, the insulation between the electrode members E_(i) isnot adversely affected.

As described above, a platinum thin film is formed on the inner wallsurface of the electrode members E_(i). Even in the case where anundetectable fouling exists on the inner wall surface of the electrodemembers E_(i), therefore, the platinum thin film formed on it preventsthe inner wall surface of the electrode members E_(i) from being chargedup. Fouling may remain in portions not directly visible from thecylinder axis of the electrode members E_(i), and the holding member 12is insulative. Therefore, these portions may be charged up. However,because they are not in directly opposed relation to the interior of thecylinder, the electric field in the cylinder is not affected adversely.

It will thus be understood from the foregoing description that accordingto this invention, there is provided an electrostatic deflector in whichthe surface of the electrode member is not even slightly charged up bythe fouling caused during assembly. Therefore, disturbance of theelectric field of the electrostatic deflector is reduced and theaccuracy of the exposure position is improved.

FIG. 6 is a perspective view showing a configuration of an electrostaticdeflector according to the second embodiment of the invention. Theelectrostatic deflector according to the second embodiment has aconfiguration of the first and second basic structures combined. In theelectrostatic deflector according to the second embodiment, only theholding member 52 is different from the conventional one shown in FIG.1, and the electrode group 11 configured of eight electrodes is the sameas the conventional electrode group shown in FIG. 1. An assemblingmethod will be explained with reference to FIG. 2.

At the time of assembly, each electrode member E_(i), while being heldin position accurately by an assembly jig, is inserted into the holdingmember 52. A small amount of soldering or brazing material 18 isinjected into the holes 61 formed in the holding member 52 (FIG. 2B) andheated. As a result, the joining metal pads 14, 15 formed on theelectrode members E_(i) and the joining metal pads 16, 17 formed on theholding member are fixed to each other. In other words, the electrodemembers E_(i) are firmly fixed in predetermined relative positions withthe holding member 52.

In the same way as described above, the electrostatic deflectoraccording to the second embodiment is realized.

FIG. 7 is a perspective view showing a configuration of an electrostaticdeflector according to a third embodiment of the invention. As shown, inthe electrostatic deflector according to the third embodiment, theholding member 52 is divided into two short holding units 52 a, 52 b.The holding units 52 a, 52 b each are a cylinder one tenth or less aslong as the electrode member E_(i), for example, and have eight holes 61formed therein. The remaining structure of the holding members 52 a, 52b is the same as the corresponding structure of the second embodiment.In other words, those portions of the holding member 52 of theelectrostatic deflector according to the second embodiment shown in FIG.6 which correspond to the length of the slots 60 are all removed, andthe holding member 52 is divided into two portions. Thus, the lowerholding unit 52 b is located at a distance at least one third of theelectrode length away from the lower end of the electrode group 11.

The electrostatic deflector according to the third embodiment has theholding member thereof divided into the two holding units 52 a, 52 b,and therefore are not assembled in the same manner as that of the secondembodiment. This electrostatic deflector is assembled into a fixed stateby injecting the soldering or brazing material into the holes 61 withthe eight electrode members E_(i) and the two holding units 52 a, 52 bfixed exactly in position using an assembly jig.

As described above, with the electrostatic deflector according to thisinvention, the charge-up of and the attachment of contaminatedsubstances to the holding member for holding the electrodes are reducedand so is the disturbance of the electric field of the electrostaticdeflector, thereby improving the accuracy of the exposure position.

What is claimed is:
 1. An electrostatic deflector of an electron beamradiation apparatus, comprising a cylindrical holding member made of anon-conductive material and a plurality of electrodes having at least apartially conductive surface separated fixedly from each other along aninner peripheral direction of said holding member, wherein said holdingmember has a plurality of elongated slots radially extending throughsaid holding member, each of said elongated slots extending in thedirection parallel to the axis of said cylinder in the portions thereoffacing the space between adjoining ones of said electrodes, therebyreducing an area of said portions on which charge can accumulate so asto reduce an effect of such accumulated charge on an electric field inthe electrostatic deflector.
 2. An electrostatic deflector of anelectron beam radiation apparatus according to claim 1, wherein aplurality of said electrodes extend in the direction of electron beamemission from said holding member.
 3. An electrostatic deflector of anelectron beam radiation apparatus according to claim 2, wherein thelength of extension of a plurality of said electrodes in the directionof electron beam emission from said holding member is longer than onethird of the length of said electrode.
 4. An electrostatic deflector ofan electron beam radiation apparatus according to claim 1, wherein saidholding member comprises a tubular wall, and the elongated slots extendthrough the tubular wall from inside to outside thereof.
 5. Anelectrostatic deflector of an electron beam radiation apparatus,comprising a cylindrical holding member made of a non-conductivematerial and a plurality of electrodes having at a least partiallyconductive surface separated fixedly from each other along the innerperipheral direction of said holding member, wherein a plurality of saidelectrodes extend in the direction of electron beam emission from saidholding member; and wherein the length of extension of a plurality ofsaid electrodes in the direction of electron beam emission from saidholding member is longer than one third of the length of said electrode.6. An electrostatic deflector of an electron beam radiation apparatus,comprising a cylindrical holding member made of a non-conductivematerial and a plurality of electrodes having at least a partiallyconductive surface separated fixedly from each other along the innerperipheral direction of said holding member, wherein said holding memberhas a plurality of independent holding units; and wherein the totallength of said holding units is less than half the length of saidelectrodes, thereby reducing an area of the holding member on whichcharge can accumulate so as to reduce an effect of such accumulatedcharge on an electric field in the electrostatic deflector.
 7. Anelectrostatic deflector of an electron beam radiation apparatusaccording to claim 6, wherein the distance from the end of the holdingunit nearest to the sample along the direction of electron beam emissionto the end of the electrodes along the direction of electron beamemission is longer than one third of the length of said electrodes. 8.An electrostatic deflector of an electron beam radiation apparatusaccording to claim 6, wherein said holding member includes a pluralityof wedge-shaped fixing holes having a larger diameter on the outerperipheral surface of said holding member than on the inner peripheralsurface thereof and arranged at positions corresponding to a pluralityof said electrodes fixed, respectively, said electrodes being fixed onsaid holding member by injecting a molten joining metal into said fixingholes with the electrodes appropriately arranged on said holding memberand setting said joining metal in close contact with the metal films ofsaid electrodes; wherein said electrodes, as fixed on said holdingmember, are so shaped that the inner wall surface of said holding memberis invisible from the cylinder axis of said holding member; and whereinsaid electrodes have a metal thin film formed by vapor deposition on theinner wall surface thereof after being fixed on said holding member.